Automated 3D build processes

ABSTRACT

A conveyor or other transport mechanism is provided to support multiple, sequential builds from a three-dimensional fabrication machine. The conveyor may be heated/cooled, coated, or otherwise treated to assist in adhesion during a build, as well as removal of objects after a build. Each fabricated object may be automatically removed from the conveyor as the conveyor moves in order to restore a buildable surface for fabrication of additional objects.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/314,337 filed Dec. 8, 2011, which is a continuation-in-partof U.S. patent application Ser. No. 12/858,622, filed on Aug. 18, 2010(now U.S. Pat. No. 8,282,380 issued Oct. 9, 2012), the entire content ofeach of these applications is hereby incorporated by reference.

BACKGROUND

The invention relates to an automated three-dimensional build process inwhich objects are automatically removed from a build surface in order topermit continuous fabrication of multiple objects.

A variety of three-dimensional fabrication techniques have been devisedto support rapid prototyping from computer models. In general, thesetechniques have been refined over the years to increase accuracy,working volume, and the variety of build materials available in a rapidprototyping environment. While these increasingly sophisticated andexpensive machines appear regularly in commercial design and engineeringsettings, a more recent trend has emerged toward low-costthree-dimensional prototyping devices suitable for hobbyists and homeusers. These devices typically provide smaller build volumes and fasterbuild times, and as a result they are used to fabricate more numerous,smaller devices, which may require frequent user intervention toretrieve completed objects from the working volume. Thus, a need hasemerged for prototyping machines that support the continuous fabricationof multiple objects in this context.

SUMMARY

A conveyor or other transport mechanism is provided to support multiple,sequential builds from a three-dimensional fabrication machine. Theconveyor may be heated/cooled, coated, or otherwise treated to assist inadhesion during a build, as well as removal of objects after a build.Each fabricated object may be automatically removed from the conveyor asthe conveyor moves in order to restore a buildable surface forfabrication of additional objects.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description of particularembodiments thereof, as illustrated in the accompanying drawings. Thedrawings are not necessarily to scale, emphasis instead being placedupon illustrating the principles of the invention.

FIG. 1 is a block diagram of a three-dimensional printer.

FIG. 2 is an isometric view of a conveyer for an automated buildprocess.

FIG. 3 is a cross-section of a conveyor.

FIG. 4 is a cross-section of a conveyor with a laminated workingsurface.

FIG. 5 is a cross section of a conveyer with a sprayed-on workingsurface.

FIG. 6 is a cross-section of a conveyor with a removable and replaceablesurface.

FIG. 7 shows a process for automated three-dimensional fabrication.

FIG. 8 shows a process for automated three-dimensional fabrication.

DETAILED DESCRIPTION

Described herein are devices and methods for automating athree-dimensional build process to accommodate continuous fabrication ofmultiple objects without user intervention. It will be understood thatwhile the exemplary embodiments below emphasize fabrication techniquesusing extrusion, the principles of the invention may be adapted to awide variety of three-dimensional fabrication processes, and inparticular additive fabrication processes including without limitationselective laser sintering, fused deposition modeling, three-dimensionalprinting, and the like. All such variations that can be adapted to usewith a continuous or similarly automated fabrication process asdescribed herein are intended to fall within the scope of thisdisclosure. It should also be understood that any reference herein to afabrication process such as three-dimensional printing is intended torefer to any and all such additive fabrication process unless a narrowermeaning is explicitly stated or otherwise clear from the context.

FIG. 1 is a block diagram of a three-dimensional printer. In general,the printer 100 may include a build platform 102, a conveyor 104, anextruder 106, an x-y-z positioning assembly 108, and a controller 110that cooperate to fabricate an object 112 within a working volume 114 ofthe printer 100.

The build platform 102 may include a surface 116 that is rigid andsubstantially planar. The surface 116 may support the conveyer 104 inorder to provide a fixed, dimensionally and positionally stable platformon which to build the object 112.

The build platform 102 may include a thermal element 130 that controlsthe temperature of the build platform 102 through one or more activedevices 132 such as resistive elements that convert electrical currentinto heat, Peltier effect devices that can create a heating or coolingeffect, or any other thermoelectric heating and/or cooling devices. Thusthe thermal element 130 may be a heating element that provides activeheating to the build platform 102, a cooling element that providesactive cooling to the build platform 102, or a combination of these. Theheating element 130 may be coupled in a communicating relationship withthe controller 110 in order for the controller 110 to controllablyimpart heat to or remove heat from the surface 116 of the build platform102. Thus the thermal element 130 may include an active cooling elementpositioned within or adjacent to the build platform 102 to controllablycool the build platform 102.

It will be understood that a variety of other techniques may be employedto control a temperature of the build platform 102. For example, thebuild platform 102 may use a gas cooling or gas heating device such as avacuum chamber or the like in an interior thereof, which may be quicklypressurized to heat the build platform 102 or vacated to cool the buildplatform 102 as desired. As another example, a stream of heated orcooled gas may be applied directly to the build platform 102 before,during, and/or after a build process. Any device or combination ofdevices suitable for controlling a temperature of the build platform 102may be adapted to use as the thermal element 130 described herein.

The conveyer 104 may be formed of a sheet 118 of material that moves ina path 120 through the working volume 114. Within the working volume114, the path 120 may pass proximal to the surface 116 of the buildplatform 102—that is, resting directly on or otherwise supported by thesurface 116—in order to provide a rigid, positionally stable workingsurface for a build. It will be understood that while the path 120 isdepicted as a unidirectional arrow, the path 120 may be bidirectional,such that the conveyer 104 can move in either of two opposing directionsthrough the working volume 114. It will also be understood that the path120 may curve in any of a variety of ways, such as by looping underneathand around the build platform 102, over and/or under rollers, or arounddelivery and take up spools for the sheet 118 of material. Thus, whilethe path 120 may be generally (but not necessarily) uniform through theworking volume 114, the conveyer 104 may move in any direction suitablefor moving completed items from the working volume 114. The conveyor mayinclude a motor or other similar drive mechanism (not shown) coupled tothe controller 110 to control movement of the sheet 118 of materialalong the path 120. Various drive mechanisms are shown and described infurther detail below.

In general, the sheet 118 may be formed of a flexible material such as amesh material, a polyamide, a polyethylene terephthalate (commerciallyavailable in bi-axial form as MYLAR), a polyimide film (commerciallyavailable as KAPTON), or any other suitably strong polymer or othermaterial. The sheet 118 may have a thickness of about three to seventhousandths of an inch, or any other thickness that permits the sheet118 to follow the path 120 of the conveyer 104. For example, withsufficiently strong material, the sheet 118 may have a thickness of oneto three thousandths of an inch. The sheet 118 may instead be formed ofsections of rigid material joined by flexible links.

A working surface of the sheet 118 (e.g., an area on the top surface ofthe sheet 118 within the working volume 114) may be treated in a varietyof manners to assist with adhesion of build material to the surface 118and/or removal of completed objects from the surface 118. For example,the working surface may be abraded or otherwise textured (e.g., withgrooves, protrusions, and the like) to improve adhesion between theworking surface and the build material.

A variety of chemical treatments may be used on the working surface ofthe sheet 118 of material to further facilitate build processes asdescribed herein. For example, the chemical treatment may include adeposition of material that can be chemically removed from the conveyer104 by use of water, solvents, or the like. This may facilitateseparation of a completed object from the conveyer by dissolving thelayer of chemical treatment between the object 112 and the conveyor 104.The chemical treatments may include deposition of a material that easilyseparates from the conveyer such as a wax, mild adhesive, or the like.The chemical treatment may include a detachable surface such as anadhesive that is sprayed on to the conveyer 104 prior to fabrication ofthe object 112.

In one aspect, the conveyer 104 may be formed of a sheet of disposable,one-use material that is fed from a dispenser and consumed with eachsuccessive build.

In one aspect, the conveyer 104 may include a number of differentworking areas with different surface treatments adapted for differentbuild materials or processes. For example, different areas may havedifferent textures (smooth, abraded, grooved, etc.). Different areas maybe formed of different materials. Different areas may also have orreceive different chemical treatments. Thus a single conveyer 104 may beused in a variety of different build processes by selecting the variousworking areas as needed or desired.

The extruder 106 may include a chamber 122 in an interior thereof toreceive a build material. The build material may, for example, includeacrylonitrile butadiene styrene (“ABS”), high-density polyethylene(“HDPL”), polylactic acid, or any other suitable plastic, thermoplastic,or other material that can usefully be extruded to form athree-dimensional object. The extruder 106 may include an extrusion tip124 or other opening that includes an exit port with a circular, oval,slotted or other cross-sectional profile that extrudes build material ina desired cross-sectional shape.

The extruder 106 may include a heater 126 to melt thermoplastic or othermeltable build materials within the chamber 122 for extrusion through anextrusion tip 124 in liquid form. While illustrated in block form, itwill be understood that the heater 126 may include, e.g., coils ofresistive wire wrapped about the extruder 106, one or more heatingblocks with resistive elements to heat the extruder 106 with appliedcurrent, an inductive heater, or any other arrangement of heatingelements suitable for creating heat within the chamber 122 to melt thebuild material for extrusion. The extruder 106 may also or insteadinclude a motor 128 or the like to push the build material into thechamber 122 and/or through the extrusion tip 124.

In general operation (and by way of example rather than limitation), abuild material such as ABS plastic in filament form may be fed into thechamber 122 from a spool or the like by the motor 128, melted by theheater 126, and extruded from the extrusion tip 124. By controlling arate of the motor 128, the temperature of the heater 126, and/or otherprocess parameters, the build material may be extruded at a controlledvolumetric rate. It will be understood that a variety of techniques mayalso or instead be employed to deliver build material at a controlledvolumetric rate, which may depend upon the type of build material, thevolumetric rate desired, and any other factors. All such techniques thatmight be suitably adapted to delivery of build material for fabricationof a three-dimensional object are intended to fall within the scope ofthis disclosure.

The x-y-z positioning assembly 108 may generally be adapted tothree-dimensionally position the extruder 106 and the extrusion tip 124within the working volume 114. Thus by controlling the volumetric rateof delivery for the build material and the x, y, z position of theextrusion tip 124, the object 112 may be fabricated in three dimensionsby depositing successive layers of material in two-dimensional patternsderived, for example, from cross-sections of a computer model or othercomputerized representation of the object 112. A variety of arrangementsand techniques are known in the art to achieve controlled linearmovement along one or more axes. The x-y-z positioning assembly 108 may,for example, include a number of stepper motors 109 to independentlycontrol a position of the extruder within the working volume along eachof an x-axis, a y-axis, and a z-axis. More generally, the x-y-zpositioning assembly 108 may include without limitation variouscombinations of stepper motors, encoded DC motors, gears, belts,pulleys, worm gears, threads, and so forth. Any such arrangementsuitable for controllably positioning the extruder 106 within theworking volume 114 may be suitably adapted to use with the printer 100described herein.

By way of example and not limitation, the conveyor 104 may be affixed toa bed that provides x-y positioning within the plane of the conveyor104, while the extruder 106 can be independently moved along a z-axis.As another example, the extruder 106 may be stationary while theconveyor 104 is x, y, and z positionable. As another example, theextruder 106 may be x, y, and z positionable while the conveyer 104remains fixed. In yet another example, the conveyer 104 may, by movementof the sheet 118 of material, control movement in one axis (e.g., they-axis), while the extruder 106 moves in the z-axis as well as one axisin the plane of the sheet 118. Thus in one aspect, the conveyor 104 maybe attached to and move with at least one of an x-axis stage (thatcontrols movement along the x-axis), a y-axis stage (that controlsmovement along a y-axis), and a z-axis stage (that controls movementalong a z-axis) of the x-y-z positioning assembly 108. More generally,any arrangement of motors and other hardware controllable by thecontroller 110 may serve as the x-y-z positioning assembly 108 in theprinter 100 described herein. Still more generally, while an x, y, zcoordinate system serves as a convenient basis for positioning withinthree dimensions, any other coordinate system or combination ofcoordinate systems may also or instead be employed, such as a positionalcontroller and assembly that operates according to sphericalcoordinates.

The controller 110 may be electrically coupled in a communicatingrelationship with the build platform 102, the conveyer 104, the x-y-zpositioning assembly 108, and the other various components of theprinter 100. In general, the controller 110 is operable to control thecomponents of the printer 100, such as the build platform 102, theconveyer 104, the x-y-z positioning assembly 108, and any othercomponents of the printer 100 described herein to fabricate the object112 from the build material. The controller 110 may include anycombination of software and/or processing circuitry suitable forcontrolling the various components of the printer 100 described hereinincluding without limitation microprocessors, microcontrollers,application-specific integrated circuits, programmable gate arrays, andany other digital and/or analog components, as well as combinations ofthe foregoing, along with inputs and outputs for transceiving controlsignals, drive signals, power signals, sensor signals, and so forth.

A variety of additional sensors and other components may be usefullyincorporated into the printer 100 described above. These othercomponents are generically depicted as other hardware 134 in FIG. 1, forwhich the positioning and mechanical/electrical interconnections withother elements of the printer 100 will be readily understood andappreciated by one of ordinary skill in the art. The other hardware 134may include a temperature sensor positioned to sense a temperature ofthe surface of the build platform 102. This may, for example, include athermistor or the like embedded within or attached below the surface ofthe build platform 102. This may also or instead include an infrareddetector or the like directed at the surface 116 of the build platform102 or the sheet 118 of material of the conveyer 104.

In another aspect, the other hardware 134 may include a sensor to detecta presence of the object 112 at a predetermined location on the conveyer104. This may include an optical detector arranged in a beam-breakingconfiguration to sense the presence of the object 112 at a location suchas an end of the conveyer 104. This may also or instead include animaging device and image processing circuitry to capture an image of theworking volume and analyze the image to evaluate a position of theobject. This sensor may be used for example to ensure that the object112 is removed from the conveyor 104 prior to beginning a new build atthat location on the working surface. Thus the sensor may be used todetermine whether an object is present that should not be, or to detectwhen an object is absent. The feedback from this sensor may be used bythe controller 110 to issue processing interrupts or otherwise controloperation of the printer 100.

In another aspect, the other hardware 134 may include a sensor thatdetects a position of the conveyer 104 along the path. This informationmay be obtained by an encoder in a motor that drives the conveyer 104,or using any other suitable technique such as a sensor and correspondingfiducials (e.g., visible patterns, holes, or areas with opaque,specular, transparent, or otherwise detectable marking) on the sheet118. In another aspect, the sensor may include a heater (instead of orin addition to the thermal element 130) to heat the working volume suchas a radiant heater or forced hot air to maintain the object 112 at afixed, elevated temperature throughout a build.

FIG. 2 is an isometric view of a conveyer for an automated buildprocess. As described above, the conveyer 200 includes a sheet 202 ofmaterial that provides a working surface 204 for three-dimensionalfabrication. As depicted, the conveyer may form a continuous path 206about a build platform 208 by arranging the sheet 202 as a belt or thelike. More specifically, the path 206 may move parallel to the surfaceof the build platform 208 along the top of the build platform 208 (fromleft to right in FIG. 2). The sheet 202 may then curve downward andaround a roller 210 and reverses direction underneath the build platform208, returning again at an opposing roller 212 to form a loop about thebuild platform 208.

The roller 210 may be coupled by gears 214 or the like to a motor (notshown) to move the sheet 202 of material. The motor may be controlled bya controller (such as the controller 110 described above) to controlmovement of the sheet 202 of material in a build process.

The conveyer 200 may include a scraper 216 to physically separate acompleted object from the conveyer 200 based upon a relative movement ofthe sheet 202 of material of the conveyor 200 to the scraper 216. Ingeneral, adhesion of an object to a working surface maintains the objectwithin the coordinate system of the printer during a build in order tomaintain precision of the build process. Where good adhesion is achievedduring a build, dislodging the completed object from the working surfacemay require significant force. Thus in order to ensure the availabilityof a continuous working surface, the conveyer 200 may enforce physicalseparation of the object from the working surface by passing the sheet202 of material by the scraper 216 to dislodge the object. While thescraper 216 is depicted below the working surface of the sheet 202, itwill be readily understood that a variety of positions and orientationsof the scraper 216 may achieve similar results. Thus for example, thescraper 216 may extend vertically above or below the sheet 202,horizontally from the sheet 202 or in any other suitable orientation. Itwill also be appreciated that while the scraper 216 is depicted in anorientation perpendicular to the path 206, the scraper 216 may be angledin order to also urge a completed object off the sheet 202 in anydesired direction, such as to a side of the working surface where achute or receptacle may be provided to catch and store the completedobject. In some embodiments, the conveyor 200 can translate to a side ofthe printer 100, so that urging the completed object off the sheet 202causes the competed object to depart the printer 100. Still moregenerally, the term ‘scraper’ should be understood as describing anon-limiting example of a physical fixture to remove an object from thesheet 202, and that many other shapes, sizes, orientations, and the likemay also or instead be employed as the scraper 216 described hereinwithout departing from the scope of this disclosure.

FIG. 3 is a cross-section of a conveyer. As generally described above,the conveyor 300 may include a build platform 302 and a sheet 304 ofmaterial passing above the build platform 302 to provide a continuousworking surface for an automated build process. In general, a motor 306or other electro-mechanical drive mechanism may control movement of thesheet 304 across the build platform 302. While the arrangement describedabove generally employs a belt arrangement that travels around the buildplatform 302, other arrangements such as a scrolling sheet may also orinstead be employed.

For example, the sheet 304 may extend past the build platform 302, andmay scroll across the build platform 302 between a first spool 308 and asecond spool 310. The sheet 304 may scroll bi-directionally across thebuild platform 302 as generally depicted by an arrow 312. As usedherein, the term ‘scroll’ or ‘scrolling’ is intended to refer to aplanar motion of the build surface across the build platform 302 fromone spool to another. Each end of the moving surface may also or insteadinclude a container bin, box, or other receptacle to provide or receivethe sheet 304 of material in a one way feeding mechanism in which thesheet 304 is sacrificially consumed or otherwise used during a buildprocess. Thus the sheet 304 may scroll between a first container 314 anda second container 316, or more generally the conveyer 300 may include avariety of rollers, gears, motors, spools, and the like to feed thesheet 304 in a bi-directional and/or one-way arrangement to provide acontinuous working surface for an automated build process.

A variety of surfacing techniques may be used for the sheet 304 ofmaterial that provides a working surface for a build.

FIG. 4 is a cross-section of a conveyer with a laminated workingsurface. In general, the conveyer 400 may move from left to right, asillustrated by an arrow 402. As the conveyor 400 moves, a second sheet404 may be laminated to the sheet 406 of material of the conveyor 400 toform a laminated working surface 408. The sheet 406 of the conveyor 400may be fed from a source such as a spool, or travel in a continuous beltas described above, or take any other path as generally described above.The second sheet 404 may be a detachable surface such as an adhesivetape or other thin film that can receive build material (such ascompleted object) on a top surface, with a bottom surface that canreadily detach from the sheet 406 of the conveyor 400 to facilitateremoval of completed objects.

FIG. 5 is a cross section of a conveyer with a sprayed-on workingsurface. The conveyor 500, which may include any of the conveyorsdescribed above, may include a resurfacer 502 such as a spray head,wetted roll, or any other assembly or collection of assemblies to applya detachable film or surface to the conveyor 500 before the surface ofthe conveyor 500 moves into a working volume for a build. While theresurfacer 502 is depicted as a spray nozzle, it will be appreciatedthat the resurface may include any device(s) suitable for applying adetachable surface to the conveyor 500, including without limitation thelaminator described above. It will further be appreciated that theresurfacer 502 may be used with one-way or bi-directional workingsurfaces, and other surface treatment devices may also be used such as asurface cleaner to remove any detachable surface(s) before resurfacing,curing devices that provide light, heat, pressure or the like to curethe detachable surface into a desired state, and so forth.

FIG. 6 is a cross-section of a conveyor with a removable and replaceablesurface. The conveyor 600 may convey one or more removable andreplaceable build surfaces 602, each of which is removably andreplaceably attached to the conveyor 600 using, e.g., snaps, clips,hook-and-loop (e.g. VELCRO) fasteners, adhesives, or any other re-usablefastening device(s) or material(s). Each one of the removable andreplaceable build surfaces 602 may be temporarily affixed to theconveyor 600 by hand or by some automated robotic or similar process,and may be removed from the conveyor 600 after a build is complete. Abuild surface 602 may then be cleaned and recycled for use in asubsequent build process.

FIG. 7 shows a process for automated three-dimensional fabrication usingthe apparatus described above.

As shown in step 702, the process 700 may begin with providing a buildplatform having a surface that is substantially planar and a conveyorformed of a sheet of material that moves in a path passing through aworking volume proximal to the surface of the build platform. The buildplatform and conveyor may, for example, be any of the build platformsand conveyors described above.

As shown in step 704, the process 700 may include heating the buildplatform prior to fabricating the object. This may include heating thebuild platform may be heated to a minimum of about one hundred degreesCelsius, about one-hundred ten degrees Celsius, or any other temperaturethat increases an adhesive force between the sheet of material (of theconveyor) and the object. The build platform may be actively heated byapplying current to one or more resistive elements within the buildplatform, or using any other suitable heating technique such asthermoelectric heating devices, infrared radiation, and so forth. Inanother aspect, the build platform may be heated indirectly by heatingthe working volume with heated air or the like. A thermistor or othertemperature sensing device may be provided on the build platform, orotherwise positioned to measure a temperature of the build platform sothat a desired target temperature can be obtained and/or maintained.

As shown in step 706, the process 700 may include fabricating an objecton the conveyor in the working volume. Fabricating the object mayinclude creating the object from a number of layers of a build material,each one of the number of layers having a two-dimensional shapecorresponding to a cross-section of the object. More generally, anytechnique for fabricating three-dimensional objects from a depositedmaterial (or multiple materials) may be suitably adapted to continuousfabrication using the systems and methods described herein.

As shown in step 708, the process 700 may include moving the conveyor toremove the object from the working volume. This may include scrolling,sliding, or otherwise moving the working surface of the conveyor fromthe working volume using, e.g., any of the techniques described above.Moving the conveyor may include any of the techniques described above.For example, moving the conveyor may include moving the conveyor in acontinuous path about the build platform in a belt configuration or thelike. Moving the conveyor may include scrolling the conveyor through theworking volume, such as from a first spool to a second spool. It willalso be understood that moving the conveyor may include moving theconveyor bi-directionally through the working volume in a process where,e.g., an object is moved out on one side while a usable working surfaceis moved in on the other, after which a complementary set of operationsare performed with another completed object moved out on the other side.

As shown in step 710, the process 700 may include cooling the buildplatform after fabricating the object. Cooling may include cooling to amaximum temperature of about forty degrees Celsius, or to any othertemperature that reduces a bonding force between the sheet of material(of the conveyor) and the object. Cooling may include passively coolingthe build platform over time, such as by including a dwell or similarpause in fabrication prior to removing the object from the conveyor.Cooling may also or instead include actively cooling the build formusing, e.g., refrigerants, expanding gas, forced cool air,thermoelectric cooling devices, or any other suitable cooling technique.

As shown in step 712, the process 700 may include removing the completedobject from the conveyor. In many build processes, a build material maybe deposited in a molten, uncured, or other liquid state that is laterhardened into a completed object with a rigid form having a bottomsurface mated to the working surface of the conveyor. When thesubstantially planar sheet of material travels around a curved surface(such as the rollers described above), the rigid, planar bottom of thecompleted object mechanically detaches from the sheet and breaks anyadhesion forces bonding the object to the sheet. Thus the movingconveyor may assist in separating a completed object from the workingsurface of the conveyor. For example, moving the conveyor may includemoving the sheet material around a curved surface that physicallyseparates the object from the conveyor. More generally, moving theconveyor may include moving the sheet of material around a convex path,thereby imparting a convex surface to the sheet of material thatmechanically separates a substantially planar mating surface of theobject. In another aspect, moving the conveyor may also or insteadinclude moving the conveyor past a scraper that moves the object fromthe conveyor. The scraper, which may be any of the scrapers describedabove, may physically detach the object from the conveyor, and/or may beangled relative to a path of the conveyor, whereby the scraper slidesthe object off the conveyor as the conveyor moves. It will be understoodthat while a curved path and/or a scraper are two techniques that workconveniently with a belt-type conveyor as described above, numerousother techniques may be suitably adapted to use with the methods andsystems described herein including without limitation robotic arms topick objects from the conveyor, sweepers that brush or scrape across thetop of a stationary conveyor to clear objects there from, and so forth.All such techniques for removing an object that would be apparent to oneof ordinary skill in the art are intended to fall within the scope ofthis disclosure.

As shown in step 714, the process 700 may include sensing a removal ofthe object from the conveyor. This may, for example, include passing thesheet of material by an optical sensor in a beam-breaking configuration,or capturing an image of the working surface and analyzing the image todetermine the presence or absence of the object. This may also includethe use of mechanical switches/sensors that physically detect an objectand convert the presence of the object into electrical signals that canbe received and processed by the controller or other processingcircuitry.

As shown in step 716, the process 700 may optionally include resurfacingthe conveyor and returning the working surface to the working volumewhere a new object may be fabricated. In some embodiments, an object isfabricated directly on the conveyor. In such embodiments, the workingsurface may be returned to the working volume without resurfacing. Inother embodiments, a sacrificial layer or material is provided on topoff the conveyor. Where the build surface detaches, the conveyor may beresurfaced. This may generally include adding a detachable surface tothe conveyor to receive an object being fabricated using, for example,any of the resurfacers or resurfacing techniques described above. Whereremovable and replaceable rigid build surfaces are employed, resurfacingmay include removably attaching a rigid build surface to the conveyor.In such embodiments, the process 700 may further include moving therigid build surface into the working volume and fabricating the objecton the rigid build surface. In other embodiments where a source ofsingle-use material is provided for a working surface, the process 700may include removing the used working surface from the working volumeand moving a new working surface into the working volume, such as wherea sheet of material is fed continuously from a spool or other dispenser.

The process 700 may then return to step 704 and repeat with a newobject. Thus in one aspect the process 700 may include fabricating aplurality of consecutive objects sequentially on the conveyor.

It will be appreciated that the process 700 described above is providedby way of non-limiting example. Numerous variations are possible, andeach of the steps may be modified, omitted, or changed in order, and newsteps may be added, all without departing from the scope of thisdisclosure. For example, steps such as sensing removal of an object maybe omitted entirely. Where the process 700 does not employ a detachablesurface, the resurfacing step may also be omitted. At the same time, theprocess 700 may be performed in parallel such that fabrication of asecond object begins before a previously-completed object has beenremoved from the conveyor, e.g., while the previously-completed objectis cooling in an area outside the working volume. Similarly, cooling maybe performed before or after an object is removed from the workingvolume. In another aspect, heating and cooling of the build platform maybe omitted entirely, or heating/cooling may be performed on a detachablesurface of the conveyor independent of the build platform. Othervariations will also be apparent, and may be adapted to use with theprocess 700 described above.

The process 700, or portions of the process 700, may be embodied incomputer executable code stored in a non-transitory computer readablemedium (such as a compact disc, hard drive, volatile or nonvolatilememory, etc.) that, when executing on one or more computing devices suchas any of the processors or processing circuitry described herein,performs some or all of the steps described above. In such embodiments,it will be understood that the object may be described in a computermodel such as a computer-automated design model, a stereolithographyfile, or any other useful computerized representation, which may in turnbe converted into a set of tool instructions that can be applieddirectly by a controller or the like to fabricate a physical realizationof the object. Thus ‘fabrication’ as described herein may also includeprocessing a computerized representation of an object to obtain toolinstructions for a three-dimensional printer or other fabricationdevice.

FIG. 8 shows a process 800 for automated fabrication of athree-dimensional object. In the process 800 of FIG. 8, an elongatedbuild platform is provided that extends beyond the working volume topermit processing of multiple objects in a sequential batch.

As shown in step 802, the process 800 may begin with providing a rigidbuild platform having a surface that is substantially planar. The rigidbuild platform may pass through and extend from the side(s) of a workingvolume of a three-dimensional printer. In general, the build platformprovides numerous, separate working surfaces that can be usedsequentially within the working volume of the printer to fabricate anumber of objects continuously (i.e., without human intervention).

As shown in step 804, the process 800 may include heating a working areaof the surface of the rigid build platform within the working volume.The rigid build platform may include a number of separate, independentlycontrollable heating elements to provide independent control overheating and/or cooling in different areas of the platform. Thus forexample, one area of the surface within the working volume may be heatedbefore and/or during a build, while another area of the surface with acompleted object that has been removed from the working volume may beconcurrently cooled prior to removal of the completed object from theplatform.

As shown in step 806, the process 800 may include fabricating an objecton the working area. In one fabrication technique, fabricating mayinclude creating the object from a number of layers of a material, eachone of the number of layers having a two-dimensional shape correspondingto a cross-section of the object. More generally, fabricating mayinclude fabricating using any of the additive fabrication techniquesdescribed above, or any other similar technique that can be adapted touse with an enlarged build platform as described herein.

As shown in step 808, the process 800 may include cooling the workingarea.

As shown in step 810, the process 800 may include moving the workingarea out of the working volume.

As shown in step 812, the process 800 may include moving a secondworking area of the surface into the working volume. This may occurconcurrently with step 810 through movement of the rigid build platformthrough the working volume to present different working areas of theplatform to the working volume.

As shown in step 814, the process 800 may include physically separatingthe object from the working area. At this time, the working area iscleared. The working area may also be resurfaced using any of thetechniques described above. The working area may then be moved back intothe working volume where the process may return to step 804 and thebuild platform may be heated for fabrication of another object.

As shown in step 816, the process 800 may include heating the secondworking area of the surface, which may occur before, during, or afterremoval of the object in step 812.

As shown in step 818, the process may include fabricating a secondobject on the second working area. Thus any number of objects may besequentially fabricated without human intervention.

As with the process 700 of FIG. 7, it will be understood that theprocess 800 described above is provided by way of non-limiting example.Numerous variations are possible, and each of the steps may be modified,omitted, or changed in order, and new steps may be added, all withoutdeparting from the scope of this disclosure. This may, for example,include the addition of many of the steps of process 700 such asresurfacing or sensing the presence of an object on a working area. Byway of further example, the rigid build platform may include three ormore working areas so that several objects can be built in series beforeremoval of an object is required. In addition, multiple working volumesmay be provided so that two or more objects can be fabricatedconcurrently, or a single object may be fabricated with sequential,overlapping builds within the working volume. Other variations will alsobe apparent, and may be adapted to use with the process 800 describedabove.

Many of the above systems, devices, methods, processes, and the like maybe realized in hardware, software, or any combination of these suitablefor the control, data acquisition, and data processing described herein.This includes realization in one or more microprocessors,microcontrollers, embedded microcontrollers, programmable digital signalprocessors or other programmable devices or processing circuitry, alongwith internal and/or external memory, any of which may serve as thecontroller described above or supplement processing of the controllerwith additional circuitry. This may also, or instead, include one ormore application specific integrated circuits, programmable gate arrays,programmable array logic components, or any other device(s) that may beconfigured to process electronic signals. It will further be appreciatedthat a realization of the processes or devices described above mayinclude computer-executable code created using a structured programminglanguage such as C, an object oriented programming language such as C++,or any other high-level or low-level programming language (includingassembly languages, hardware description languages, and databaseprogramming languages and technologies) that may be stored, compiled orinterpreted to run on one of the above devices, as well as heterogeneouscombinations of processors, processor architectures, or combinations ofdifferent hardware and software. At the same time, processing may bedistributed across devices such as the various systems described above,or all of the functionality may be integrated into a dedicated,standalone device. All such permutations and combinations are intendedto fall within the scope of the present disclosure.

In other embodiments, disclosed herein are computer program productscomprising computer-executable code or computer-usable code that, whenexecuting on one or more computing devices (such as the devices/systemsdescribed above), performs any and/or all of the steps described above.The code may be stored in a computer memory, which may be a memory fromwhich the program executes (such as random access memory associated witha processor), or a storage device such as a disk drive, flash memory orany other optical, electromagnetic, magnetic, infrared or other deviceor combination of devices. In another aspect, any of the processesdescribed above may be embodied in any suitable transmission orpropagation medium carrying the computer-executable code described aboveand/or any inputs or outputs from same.

It will be appreciated that the methods and systems described above areset forth by way of example and not of limitation. Numerous variations,additions, omissions, and other modifications will be apparent to one ofordinary skill in the art. Thus, the order or presentation of methodsteps in the description and drawings above is not intended to requirethis order of performing the recited steps unless a particular order isexpressly required or otherwise clear from the context.

While particular embodiments of the present invention have been shownand described, it will be apparent to those skilled in the art thatvarious changes and modifications in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the following claims. The claims that follow are intended toinclude all such variations and modifications that might fall withintheir scope, and should be interpreted in the broadest sense allowableby law.

What is claimed is:
 1. An apparatus comprising: a build platformincluding a surface that is rigid and substantially planar, the surfaceincluding a plurality of areas; an extruder including a chamber toreceive a build material and an extrusion tip that extrudes the buildmaterial at a controlled volumetric rate; a x-y-z positioning assemblyadapted to three-dimensionally position the extrusion tip within theworking volume; a controller electrically coupled to each of the buildplatform, the extruder, and the x-y-z positioning assembly, thecontroller operable to control the build platform, the extruder, and thex-y-z positioning assembly to fabricate an object in three-dimensionsfrom the build material; and a plurality of heating elements disposedwithin the build platform, each one of the plurality of heating elementsassociated with a corresponding one of the plurality of areas of thesurface of the build platform, each one of the plurality of heatingelements coupled in a communicating relationship with the controller,wherein the controller is configured to independently control each oneof the plurality of heating elements to provide different heating toeach one of the plurality of areas of the surface of the build platform.2. The apparatus of claim 1 wherein at least one of the plurality ofheating elements includes a resistive element to convert electricalcurrent into heat.
 3. The apparatus of claim 1 wherein at least one ofthe plurality of heating elements includes a Peltier effect device. 4.The apparatus of claim 1 further comprising at least one cooling elementcoupled to the controller and configured to provide active cooling to anarea of the build platform.
 5. The apparatus of claim 1 wherein theplurality of heating elements includes at least one gas heating device.6. The apparatus of claim 1 further comprising at least one stream ofheated gas directed toward the build platform and controllable to heatthe build platform.
 7. The apparatus of claim 1 further comprising atleast one stream of cooled gas directed toward the build platform andcontrollable to cool the build platform.
 8. The apparatus of claim 1further comprising at least one sensor to detect a temperature of thebuild platform.
 9. The apparatus of claim 1 further comprising at leastone radiant heater configured to heat the working volume during a build.10. The apparatus of claim 1 further comprising at least one radiantheater configured to maintain the object at a fixed, elevatedtemperature during a build.
 11. The apparatus of claim 1 wherein theplurality of heating elements provide independent control over coolingthe plurality of areas of the surface of the build platform.
 12. Theapparatus of claim 1 further comprising a conveyor to controllably movethe object out of the working volume.
 13. The apparatus of claim 1wherein the plurality of heating elements are controllable to heat atleast one of the plurality of areas of the surface of the build platformto at least about one hundred degrees Celsius.
 14. A method comprising:providing a build platform having a surface that is substantiallyplanar, the surface including a plurality of areas, the build platformpassing through a working volume of a three-dimensional printer;independently controlling a plurality of heating elements for the buildplatform to provide different heating to each one of the plurality ofareas of the surface of the build platform; and fabricating an object onthe build platform, wherein fabricating the object includes creating theobject from a number of layers of a material, each one of the number oflayers having a two-dimensional shape corresponding to a cross-sectionof the object.
 15. The method of claim 14 further comprising activelycooling the build platform after fabricating the object.
 16. The methodof claim 14 further comprising moving the object out of the workingvolume with a conveyor after fabricating the object.
 17. A computerprogram product for controlling a three-dimensional printer, thecomputer program product comprising computer executable code embodied ina non-transitory computer-readable medium that, when executing on one ormore computing devices, performs the steps of: controlling athree-dimensional printer to fabricate an object on a build platformwithin a working volume of the three-dimensional printer, the buildplatform having a surface that is substantially planar, the surfaceincluding a plurality of areas, wherein fabricating the object includescreating the object from a number of layers of a material, each one ofthe number of layers having a two-dimensional shape corresponding to across-section of the object; and independently controlling a pluralityof heating elements for the build platform to provide different heatingto each one of the plurality of areas of the surface of the buildplatform.
 18. The computer program product of claim 17 furthercomprising code that performs the step of moving the object out of theworking volume with a conveyor after completing a fabrication of theobject.